#include <unistd.h>
#include <err.h>

int main()
{
   if(daemon(0,0) == -1)
       err(1, NULL);

   while(1)
   {
      /* do stuff */
   }
}

#!/bin/sh
#
# This script will be executed *after* all the other init scripts.
# You can put your own initialization stuff in here if you don't
# want to do the full Sys V style init stuff.

# Run my-daemon in the background
/usr/sbin/my-daemon

#include <unistd.h>

int main()
{
   close(0);
   close(1);
   close(2);
   chdir("/");

   while(1)
   {
      /* do stuff */
   }
}

#
# inittab       This file describes how the INIT process should set up
#               the system in a certain run-level.
#

# [ snip for brevity ]

# Run only in runlevel 5. Init will kill my-service if
# another runlevel is selected. If it crashes quickly
# and repeatedly, init will stop restarting it for 5 minutes.

mine:5:respawn:/usr/sbin/my-service